You will receive a margin call SMS when there is a margin shortfall in your futures and/or options position owing to losses in the position. You will then have to either add funds to your trading account or reduce position size. 
To know how much money you need to add, go to the funds section from the top right corner of your home screen. If the available margin is negative, you have to bring in that much amount to cover the shortfall. 

To continue holding your position you are required to add funds to your trading account, failing which the position will be squared-off by our Risk Management System. If in case a position wasn't squared off there could be penalty charged by the exchange for holding a position overnight if you do not have the sufficient margin.